In a machining operation such as, for example, cutting, drilling, milling, shearing, etc., it is frequently necessary to machine a large number of similar or different work pieces. A work piece is typically held during the machining operation by a work piece positioning device such as, for example, a vice with a pair of opposing gripping jaws. For such operations, each work piece is positioned at a desired location in relation to the machining device to ensure that each work piece is machined properly. The same work pieces are typically positioned at the same location. When the machining process is computer controlled, the computer often controls the machining of each work piece relative to a zero reference point programmed into the computer controls.
The prior art includes various stop gauge assemblies, each having a stop surface against which a work piece is positioned in order to locate the work piece for machining. For example, U.S. Pat. No. 5,197,721 to Ruberg discloses a device attachable to a milling machine vise for positioning a work piece between a pair of vise jaws. The device described in the Ruberg patent includes a bar clamped to a top surface of a vise and an intermediate member connected to the end of the bar. The intermediate member has a leading end mounting a work piece contacting rod. The contacting rod has a contact or stop surface and is adjustable so as to secure its stop surface at a desired location, relative to the machining device. The work piece is positioned against the stop surface, gripped in the vise jaws and then machined. If the work pieces are relatively identical, once the position of the stop surface is set, all of the work pieces can be machined similarly with a high degree of consistency between the work pieces. If the work piece changes, then the position of the stop surface typically needs to be repositioned.
One problem with the device described in the Ruberg patent is that the contacting rod, and therefore the stop surface, cannot be positioned at a desired location and repositioned to a different location with a high degree of precision. The inability to position the stop surface of the Ruberg device, and therefore the work piece, with a high degree of precision makes it more difficult and time consuming, if not impossible, to machine a work piece with a high degree of precision, in particular by computer control.
Accordingly, there is a need for a stop gauge assembly which can position a work piece to a desired location and reposition the work piece to a different location with a high degree of precision.